Google employs at least 20k engineers. I'd be shocked if 100 quit over this news.
Google could be murdering kittens to cool servers with their blood and you could probably find enough competent engineers to keep 10 Google's fully staffed. The vast majority of people do not give two shits.
Everybody dies anyway, nobody is remembered, or gets to keep anything; we can build what we want, end result is the same. The only brief moment of reality is our experience of the universe and the kind of life we lead, and if what you claim true for "the vast majority of people" was true, IMO that would just mean the vast majority are deeply sick and probably frightened shitless of death. That'd no doubt be very important for them, but how would it matter for me? Should I jump into their pool, to drown alongside them and make them feel better?
I'm also saying that people who are saying this will hurt Google or make it hard for them to hire new people are flat-out wrong.
All it takes is for a few good people to do nothing...
Additionally, leaving a secure, well-paid role in political protest takes a certain amount of privilege. My father left an amazing job in protest over immoral actions and I can assure you that it had huge financial impacts on my life growing up. I respect him for his decision and I like to think I'd make the same one, however, I can understand how people even less fortunate aren't making political choices with their employment.
Good.
It's not like a good, ethical developer is going to change things from the inside. Companies are not democracies, they are dictatorships.
So what if Google has no good and moral developers left? At least it will become more obvious what Google truly is while the 'good' developers can make a positive contribution elsewhere. It was clearly never going to happen at Google anyway, not with a incentives a publicly-traded company has.
I would much prefer Google to be manned entirely by the kinds of people I wouldn't dream of inviting into my home. I'm already against the company's existence, so Google having nobody left with a shred of integrity or backbone would make it a whole lot easier to argue for the company's demise, in whatever shape that may come.